The long-term objective of this work is the development and application of synthetic methods for the preparation of structurally diversified amino acid derivatives. New and practical synthetic routes for the preparation of amino acid analogs are of fundamental importance because of the widespread use of these compounds in practically all areas of the physical and life sciences. The methodology will be pursued on two complimentary fronts: nucleophilic and electrophilic synthons which utilize Schiff base protecting groups. The nucleophilic substrates will be used in a novel controlled monoalkylation sequence. Of particular interest in this regard is the application of catalytic phase-transfer alkylation procedures to these systems. Use of the protected amino acids as electrophiles, equivalent to an Alpha-cationic amino acid synthon, will allow for the preparation of a variety of amino acid analogs which are not easily accessible by the nucleophilic route: Alpha-aryl-, Alpha-vinyl-, Alpha-heterosubstituted-amino acids and amino acids containing a beta-tertiary carbon center. Asymmetric syntheses will be studied for both systems: use of a chiral phase-transfer catalyst with the nucleophilic synthons and chiral auxillaries in the case of the electrophilic equivalents. Finally, application of the two general methods will be further demonstrated by the synthesis of four natural and/or rare amino acids.